Problems with self-control are of major public health relevance as they are associated with physical and mental health, substance abuse and academic success impacting both individuals and society. The development of self-control is a critical step toward successful independence in young adulthood. Attention- deficit/hyperactivity disorder (ADHD) is a highly prevalent disorder associated with elevated problems with self- control. We hypothesize that poor self-control in ADHD leads to their impaired academic achievement and poor high school graduation rates. An improved understanding of the developmental trajectory of self-control will lead to more focused and successful intervention programs. Despite the public health importance of self-control, no studies have directly tested how the underlying mechanisms that determine self-control develop. It is hypothesized that a balance between cognitive control and reward response processes determine degree of self-control functioning. This project will characterize for the first time how cognitive control and reward-related neural functioning during adolescence and early adulthood independently contribute to self-control in both healthy development and ADHD. We will assess how changes in brain development occur in a two system model of self-control, which includes cognitive control (dorsolateral prefrontal cortex) and reward processing (ventral striatum) systems, and how the systems relate to broader impairments associated with ADHD. An additional goal is to assess if brain activity associated with self-control can serve as a biomarker for predicting academic performance. At the conclusion of these studies we will be able to identify age-related specific targets and recommendations for improving self-control. This work is a team effort by ADHD and functional imaging cognitive control researchers Julie Schweitzer and Catherine Fassbender at the UC Davis MIND Institute; Amanda Guyer at UC Davis with expertise in reward and emotional systems in neurodevelopment; Jamal Abedi at UC Davis with proficiency in measuring academic outcomes; and from Stanford University Samuel McClure, developer of the two-system model of self- control in neuro-economics, and Wouter van den Bos with experience in the development of social and reward based decision-making. Stephen Hinshaw at UC Berkeley brings to the contribution experience in ADHD, diagnostic issues, longitudinal research methods, measurement of academic issues in ADHD and general outcome research methods associated with the disorder. The geographic proximity of these collaborators from northern California will help to facilitate this collaboration. This project is consistent with th aims of the NIMH Strategic Plan Objective 2: Charting Mental Illness Trajectories to Determine When, Where and How to Intervene. The project also overlaps with NIDA Strategic Plan Goal 1: To prevent the initiation of drug use and the escalation to addiction considering ADHD and problems with self-control are related to higher rates of substance abuse.